IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
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14 Jan 2021
Face to Face with a Dark Filament
Credit: IRIS, LMSAL/NASA, Lucas Guliano
A recent IRIS movie of the day took a look at an interesting filament from September that we were able to observe both on-disk with darker absorption and off disk as a bright prominence. The above movie, taken on January 7th, 2021, shows three scans of a more direct look at the darker side of filaments located on the Solar Disk. As IRIS scans through the wavelengths observed through the slit, it reaches the the Mg II K line. When observing the Sun in this specific wavelength, the dark curved shape of the filament reveals itself. This region on the Sun is of course still remarkably hot and bright by any Earthly standard. But compared to the rest of the solar atmosphere it appears as a dark structure. The advantage of IRIS as a spectrograph imager is that it can shed light on interesting structures such as these that would otherwise remain in the dark.